I originally had the non-leather (Duraflo?) binders. Left 'em on the glareshield at Mudgee one very hot day and came back to find one of them had nearly liquefied! Looked like a brown candle.
Jepp very kindly changed them for cowhide at no cost.
The paper's fine. Although it's thin, it's very strong and seems to last better than DAPS (the better binder mechanism probably helps).